Kinetic study of the oligomerization of styrene in the presence of α-thioglycerol – comparison between batch and semi-batch processes

The oligomerization of styrene in the presence of α-thioglycerol, a functionalized thiol, was studied in order to control the synthesis of ω-dihydroxylated polystyrene oligomers. Two different reaction processes were investigated: a batch process, where all the reactants are mixed together at the beginning of the reaction and a semi-batch process, where the thiol is slowly added to the reaction medium with a constant flow rate. A kinetic study performed by SEC indicated for a batch process an important drift of the reaction medium composition. As far as the semi-batch process is concerned, by adding the thiol with a controlled feed of thiol, monomodal oligomers could be obtained resulting in an excellent yield and a functionality in the range of 0.8 even at high monomer conversion. Moreover, MALDI-TOF mass spectrometry of samples obtained by both processes allowed us to demonstrate the presence of very low molecular weight oligomers and of non-functionalized oligomers.